Aryldiazonium chlorides

Arylpentazoles can be prepared by adding an aqueous solution of azide to a mixture of an aryldiazonium chloride, aqueous methanol, and petroleum ether at —40 to —20° with stirring. The pure aryl-pentazole (see Table I) crystallizes from the two-phase reaction mixture the inorganic impurities remain in the aqueous methanol and the organic impurities in the petroleum ether. 

Arylhydrazono-6,7,8,9-tetrahydro-4//-pyrido[],2-u]pyrimidin-4-ones 154 were obtained from 6,7,8,9-tetrahydro-4//-pyrido[l,2-u]pyrimidin-4-ones 153 with aryldiazonium chlorides in the presence of NaOAc 3H2O at 0 °C overnight (96JHC799, 99MI12, 00MI22). 

Dehydrohalogenation of the 314 proceeded in excellent yield under the action of morpholine or piperidine at rt, during double bond formation between the C-l and C-2 atoms <2003CHE640>. The active methylene group of 3,4-dihydro-1 ///>//-[ 1,4 oxazino[3,4- quinazolin-6-onc 315 readily condensed with aromatic aldehydes at 160 °C in a melt to give the 1-benzylidenes, and coupled with aryldiazonium chlorides to give the arylhydrazono derivatives <1996BMC547>. 

Reaction of melatonin with various aryldiazonium chlorides in ethanolic sodium acetate solution afforded arylazo-melatonin derivatives. Reactions of these products with either malonitrile or ethyl cyanoacetate formed the corresponding ary lam inotriazino[4,3-/z indole scaffolds 60-63 <2005BMC1847>. 

Reactions of phenylhydrazine with 6-bromo-6,7,8,9-tetrahydro (128) and 6,6-dibromo-6,7,8,9-tetrahydro- and -1,2,3,4,6,7,8,9-octahydro-l l//-pyrido-[2,1 -6]quinazolin-l Tones (129), and reactions of aryldiazonium chlorides with 6,7,8,9-tetrahydro- and l,2,3,4,6,7,8,9-octahydro-ll//-pyrido-[2,1 -6]quinazolin-l 1 ones (130 and their 6-substituted derivatives (131-133) yielded 6-arylhydrazono-6,7,8,9-tetrahydro- and 1,2,3,4,6,7,8,9-octahy-dro-ll//-pyrido[2,l-6]quinazolin-ll-ones (134) (Scheme 4) (84JHC1301 87JHC1045). 

With aryldiazonium chlorides the pyrido[l,2-a]pyrimidines (63 R = H) yielded the 3-arylazo derivatives.253 The 3-methyl derivative of 63 (R = H) was also subjected to diazo coupling, but the product, a 3,3-disubstituted pyrido[l,2-a]pyrimidine, underwent immediate transformation involving hydrolysis of the C-4—N-5 bond253 (see also Section III.C,4). 

Arylalkanoic acids, 109 Arylanthranilamides, 367 4-Arylbutanoic acids, 321 Aryl diazoalkanes. 565 Aryldiazonium chlorides. 495 Aryllead triacetates, 31-32... 

Arenesulfonyl chlorides.1 Aryldiazonium chlorides are converted into arenesul-I onyl chlorides by reaction with S02 and CuCl. Yields from the corresponding aniline arc 30 90%, being highest with anilines substituted with electron-withdrawing substituents. 

Malonyl-a-aminopyridine (37) reacted with aryldiazonium chloride in ethanol in the presence of sodium acetate to give 3-arylhydrazono-2,4-dioxopyrido[ 1,2-a]pyrimidines (89MI6). Heating compound 37 in for-... 

Reaction of aryldiazonium chlorides with sodium 6,9-dimethyl-6,7,8,9-tetrahydro- and 1,6-dimethyl-l, 6,7,8-tetrahydro-4-oxo-4//-pyrido[l, 2-u]pyrimidine-3-carboxylates 582 and 17 in water in the presence of sodium acetate at 5°C gave 9-(aryldiazo) derivatives 583 and 584 (83JMC1126). 

In place of sodium hydroxide, sodium acetate may be added to the mixture of diazonium salt solution and the aromatic liquid.6 Another variation, introduced by Hodgson and Marsden,6 consists in converting the aryldiazonium chloride to a stabilized diazonium salt by treatment wi,th naphthalene-l-sulfonic acid, naphthalene-1,5-disulfonic acid, or zinc chloride the dried salt is then suspended in an aromatic liquid and treated with sodium acetate and acetic anhydride. 

Schmidt11 suggested that the coupling reaction be carried out in neutral solution and without a catalyst. The best yields were obtained when the aryldiazonium chloride reacted with dipotassium arsenite in aqueous solution. 

The interaction of furan and aryldiazonium chlorides in the presence of alkali leads to 2-arylfurans, e.g., 2-phenyl-, 2-p-halophenyl-, and 2-p nitrophenylfuran however, the yields are low (15-22%). ... 

The free radical arylation of thiazole (391) has been performed either by the Gomberg-Bachmann (392) decomposition of aryldiazonium chlorides (119,393), by the thermal decomposition of benzoyl peroxide (394-397) or N-nitrosoacetanilide (398), or by the photolysis of benzoyl peroxide or iodobenzene (398). The three monophenylthiazoles are obtained in the practically constant proportions 2-phenyl, 60% 5-phenyl, 30% 4-phenyl, 10%, giving the order, 2>5>4, of decreasing reactivity of the three positions of thiazole toward phenyl radicals (398). Competition reactions with nitrobenzene (397) gave an estimation of the globed reactivity of thiazole relative to benzene of 0.75 with the partial rate factors f2 = 2.2, /s=1.9, /4 = 0.5. When the thermolysis of benzoyl peroxide is performed in acetic acid solution, the substrate in reaction is the conjugate acid of thiazole the global reactivity is enhanced to 1.25,... 

Aryldiazonium tetrahaloborates, ArN=NBX4, In the Schiemann reaction, an arylamine is diazotized in aqueous hydrochloric acid solution, and the solution or suspension of aryldiazonium chloride is treated with a solution of fluoroboric acid prepared by dissolving boric acid with cooling to 20-25° in commercial 50-60% hydrofluoric acid contained in a reaction flask coated with wax or lined with copper, lead, or silver. The aryldiazonium tetrafluoroborate is collected, dried, and decomposed by pyrolysis. Examples are ... 

Amino-5-imino-3-pyrazolidinones have been synthesized by reduction of the corresponding oximes.644,1339 Such amines form ureas and thioureas by reaction with potassium cyanate in acid solution and with phenyl isothiocyanate.644 4-Arylimino-5-imino-3-pyrazolidinones have been prepared by reaction of the 5-imino-3-pyrazolidinones with p-amino-A.-AT-diethylaniline in the presence of silver salts as oxidizing agents (eq. 172).244,519,1255,1538 4-Arylazo-5-imino-3-pyrazolidinones have most frequently been prepared by reaction of 5-imino-3-pyrazoli-dinones with aryldiazonium chlorides, as is usual for the preparation of similar compounds.591,594,920,1087,1255,1339,1539,1649 One such compound has been prepared by the Curtius rearrangement of the corresponding 4-arylazo azide.594... 

It has been shown (98JFC(92)101) that the reaction of hydrazine in Et20 and hydroxylamine hydrochlorides in CH3OH in the presence of NaOAc with ethyl-2-(/wa-methoxyphenyl)-hydrazone-4,4,4-trifluoro-2,3-dioxobutanoate 57, obtained by reactions of 1,3-ketoesters with aryldiazonium chloride, gives 3-nonafluorobutyl-4(/wa-methoxyphenyl)hydrazonepyrazolin-5-one 58 and 3-fluoromethyl-4(/wa-methoxyphenyl)hydrazonepyrazolin-5-one 59, respectively (98JFC(92)101) (Scheme 52). 

Today, the GBH reactions are performed by using aryldiazonium tetrafluoroborate salts. An aromatic amine is diazotized at about -10 to 0 C in the presence of at least 3 equivalents of concentrated hydrochloric acid by adding the solution of sodium nitrite [61]. To the aryldiazonium chloride, 50% aqueous solution of tetrafluoroboric acid is added with additional cooling to precipitate the corresponding aryldiazonium... 

To a concentrated hydrochloric acid (37%, 250 ml, 3 mol) precooled to -5 C, a liquid arylamine (1 mol) was added dropwise, or in several portions (for solids) during 15 min. The mixture was stirred at -5 °C for an additional 45 min (solid amines has to be grounded to fine powder). A solution of sodium nitrite (69.00 g, 1 mol, 1 eq.) in distilled water (250 ml) was added dropwise at -10 to -5 C during 1 h. The reaction mixture was stirred at -5 °C for an additional 1 (-2) h, until the TLC analysis shows the disappearance of the starting amine. To the obtained clear yellow solution of aryldiazonium chloride, 48% aqueous solution of tetrafluoroboric acid (150 ml, 100.80 g, 1.15 mol, 1.15 cq.) was added dropwise at -5 °C during 15 minutes. The mixture was stirred at -10 °C for 30 minutes, and the crystals were collected by filtration, washed with precooled (+5 °C) water (3x20 ml), and dried at 30 C in high vacuum for 20 h. The pure aryldiazonium tetrafluoroborates were obtained in 60-90% yields. 

---